Probably a bandsaw, with a little jig to hold the cylindrical logs.
A chop-saw, mitre saw or compound mitre saw would do it nicely too, but is a bit fiercer so you’d lose half the wood - the blade kerf is probably going to be at least 3mm.

There shouldn’t be any wandering on the bandsaw blade unless it is either blunt or not installed correctly. My bandsaw will only go up to about 80mm, but with the rip blade, it goes through most stuff pretty nicely, and requiring minimal finishing afterwards.

You coming for a visit this evening? Can have a chat about it then if you are.

There is an alternative in the form of a mitre saw, which gives you accurate 90 degree cuts for the sake of material loss compared to a bandsaw. Not sure who’s it is, but I believe there is one of these in the space. Probably Matt’s.